1. Field of the Invention
The present invention relates to a phosphorus-containing catalyst prepared from a clay starting material and to a hydrocarbon catalytic cracking process utilizing the catalyst.
2. Description of the Prior Art
Catalytic cracking processes in which a hydrocarbonaceous oil is converted to lower boiling hydrocarbon products in the presence of cracking catalysts are well known. Catalysts comprising a zeolite and a silica-alumina residue made from a calcined clay starting material in which the zeolite is produced in the clay are known. See, for example, U.S. Pat. No.3,663,165, the entire content of which is hereby incorporated by specific reference.
It is also known to produce low alkali metal content zeolites by cation exchanging, followed by calcination at a temperature of 400.degree. to 1500.degree. F. followed by at least an additional ion exchange step. See, for example U.S. Pat. No. Re 28,629 which is a reissue of U.S. Pat. No. 3,402,996, the teachings of which are hereby incorporated by specific reference.
U.S. Pat. No. 4,325,813 discloses the preparation of a clay derived zeolitic catalyst using repeated contact with an ammonium salt solution to exchange readily exchangeable sodium ions followed by calcination and re-exchange with an ammonium salt to reduce further the alkali metal content. The catalyst contained 0.20 weight percent Na.sub.2 O (see column 5, lines 41 to 51).
U.S. Pat. No. 4,048,284 discloses multistage ion exchanging of sodium on zeolite-containing microspheres.
British Pat. No. 1,524,123 discloses the preparation of a clay derived zeolite. The sodium content of the catalyst is reduced to less than about 1 weight percent by either of two exchange processes. In the second process, the product is exchanged twice with ammonium sulfate solution and once with rare earth metal salt solution.
U.S. Pat. No. 3,595,611 discloses reducing the sodium content of the zeolite via steps of ammonium exchange, then rare earth exchange, calcination and further ammonium exchange. Example 4 describes applying this ion exchange method to a faujasite prepared from calcined clay.
U.S. Pat. No. 3,375,065 discloses cation exchanging a zeolite by a sequence which comprises cation exchange with ammonium ions, followed by heat treatment at a temperature above 350.degree. F., and further cation exchange with ammonium, followed by cation exchange with magnesium, rare earth and mixtures thereof.
U.S. Pat. No. 3,676,368 discloses a sequence of ion exchanging a zeolite with rare earth ions, calcination of the exchanged zeolite, and exchanging the calcined zeolite with ammonium ions. The final exchange may be conducted on the zeolite alone or on the zeolite incorporated in a conventional matrix.
U.S. Pat. No. 4,036,739 discloses hydrothermally stable and ammonia stable Y zeolite in which a sodium Y zeolite is ion exchanged to partially exchange sodium ions for ammonium ions, steam calcined and further ion exchanged with ammonium ions to reduce the final sodium oxide content to below 1 weight percent, and calcining the reexchanged product, or according to U.S. Pat. No. 3,781,199, the second calcination may be conducted after the zeolite is admixed with the refractory oxide.
It has now been found that a catalyst comprising a clay derived zeolite and phosphorus prepared by a specified method has increased activity for cracking hydrocarbonaceous feeds.